Automated machinery is becoming increasingly common in many environments. Many modern factories and manufacturing plants include automated machinery to manufacture or process goods. Such automated machinery can include a wide range of machines, such as robots, conveyors, clamps, pins, welders and other machines. Automated machinery can also be used in environments other than factories and manufacturing plants. For example, car washes can use automated brushes and sprayers to wash cars.
Automated machinery typically requires various operations to be performed in a specific order. To increase the efficiency of automated machinery, the time between many operations should be as small as possible. As a result, various methods have been developed for machines to perform operations in a specific order while also attempting to minimize the time between operations.
An early method of minimizing the time between operations includes timing the machinery to perform each operation at a specific time. For example, if performance of a second operation requires that performance of a first operation be complete, one can determine when each cycle of the first operation will be complete. One can then time cycles of the second operation to begin almost immediately after each cycle of the first operation is complete. However, controlling the performance of various operations on the sole basis of time can have drawbacks. For example, if the first operation is not complete at its normal time due to a machine defect or some other malfunction, the second operation may still be attempted after the expected completion time of the first operation.
A more modern method includes using analog sensors to determine the status of at least some of the various operations performed by the machinery. The machinery can include multiple individual machines, and each individual machine can include one of the analog sensors. A central control center, e.g., a computer, can receive signals from the sensors by connecting respective output lines from the sensors to the central control center, and the central control center can also control each individual machine by connecting each machine to the central control center with respective input lines. For example, an analog sensor for determining whether a pneumatic clamp is open or closed can be coupled to a central control center via an output line, and a pressure source for operating the clamp can be coupled to the central control center via an input line for controlling operation of the clamp.
The central control center can thus determine the status of each individual machine (and thus each individual operation), and the control center can thereby determine whether a first operation is complete before instructing the next machine to perform a second operation. Returning to the above example involving the pneumatic clamp, if the clamp is used to hold a component while a welding operation is performed, the control center can receive a signal indicating that the welding operation is complete. After receiving this signal, the central control center can cycle through a check of all signals, can determine that the conditions for operating the clamp have been met, and can provide an input signal to the pressure source, causing the pressure source to provide pressure to or release pressure from the pneumatic clamp. The pneumatic clamp, in turn, can open to release the component, and its analog sensor can output a signal to the central control center indicating that the clamp is open. The central control center can then cycle through a check of all operations to determine that the welding operation and the clamping step are complete, and can instruct another machine to perform the next operation.